Second-generation International Space Station Total Organic Carbon Analyzer Verification Testing and On-orbit Performance Results

Abstract

The International Space Station (ISS) total organic carbon analyzer (TOCA) is designed to autonomously assess recovered water quality by providing an indication of total organic carbon (TOC). The current TOCA has been on the ISS since November 2008. Functional checkout and operations revealed complex operating considerations. Specifically, failure of the hydrogen (H 2 ) catalyst resulted in development of an innovative oxidation analysis method. This method reduces activation time and limits the H 2 produced during analysis, while retaining the ability to indicate TOC concentrations within 25% accuracy. Subsequent testing and comparison to archived samples returned from the station and tested on the ground yield high confidence in this method, and in the quality of the recovered water.

Measurement of CO2 in Water from an Ultraviolet Oxidizer for a Space-Worthy Wastewater Recovery System Using Raman Spectroscopy

“…In terms of the TOCA volume and mass, elimination of the gas phase loop would reduce these parameters by an estimated 50%, while the addition of a Raman analyzer would only contribute 2 L and 3 kg. Current efforts by other researchers include replacing the boron-doped diamond coated electrode oxidizer in the liquid loop, which is large and massive, 8 with a much smaller ultraviolet LED array. 9 These ongoing efforts should allow meeting the requirements for the next generation TOCA.…”

“…[2][3][4][5][6] While methods to recycle food are under development, 2 NASA has been developing and testing a wastewater recovery system (WRS), both on earth and on the International Space Station (ISS) for more than two decades. [5][6][7][8] The current WRS recovers ∼90% of the wastewater, which could reduce the water requirement to ∼5000 kg, but the system components are considered too large and massive. The WRS is comprised of the urine processor assembly (UPA) and the water processor assembly (WPA).…”